During the fabrication of a semiconductor device, the semiconductor substrate goes through different cycles of process. Very often the surface of the semiconductor substrate requires oxidation, etching or native oxide removal. The surface of semiconductor substrate may be treated by, for example introducing atomic hydrogen at high temperature to remove native oxide, wet chemical oxidation that involves rinsing the semiconductor substrate with liquid, and digital etching process which needs to be switched between different reaction conditions.
However, when the substrate contains silicon, germanium, silicon germanium or other III-V element, high temperature treatment may result in additional metallic species formation on the semiconductor substrate. The wet chemical oxidation process produces an oxide film that has poor stoichiometry. Digital etching requires complicate switching between, for example O3/H2O and HF/H2O. Thus, a more efficient and effective approach is needed to perform oxidation/removal of the semiconductor substrate.